Examine the system of equations.
y = 3
2
x − 6,
y = −9
2
x + 21
Use substitution to solve the system of equations. What is the value of y?

y =

Frank has a devised a formula for his catering business that calculates the number of meatballs he needs to prepare. the formula is m=4a+2c, where c=number of children; m=number of meatballs; a=number of adults. how many meatballs are required for a party of 10 adults and 5 children?